Process for dyeing cellulose acetates



RENE CLAVEL, OF BASEL-AUGST, SWITZERLAND.

PROCESS FOR DYEING CELLULOSE AOETATES.

No Drawing.

To all whom it may concern.

Be it known that I, RENE CLAVEL, a citizen of the Swiss Republic, and resident of Basel-Angst, Switzerland, have invented a new and useful Process for Dyeing Cellulose Acetates, of which the following is a full, clear, and exact specification.

It is known that cellulose acetate, such as cellulose acetate silks, cellulose acetate films and the like cannot be directly dyed in practice by the usual dyeing methods such as are used, for example, for artificial silk, because the power of taking up the dyestuif is completely or essentially lacking.

There are various processes for treating cellulose acetate silks and cellulose acetate films with inorganic or organic compounds before they are dyed, in order to increase the capacity of the fiber for taking up the dye in the dyeing operation. None of these processes has found technical applicationin the art because such preliminary treatment gives rise to tendering and loss of the cellulose acetate. Furthermore, treatment with alkalis at high temperatures gives rise to undesirable losses in the luster of the cellulose acetates under treatment.

The present invention relates to a process for directly dyeing cellulose acetates, cellu lose acetate silks and cellulose acetate films, consisting in dyeing them with acid, basic or direct dyestuffs, preferably with addition of one or more protective colloidssuch as gelatin or gelatin soaps, in presence of a weak acid, preferably an organic acid like acetic acid or formic-acid, and in presence of at least one chlorid soluble in water, such as a chlorid like stannous chlorid, zinc chlorid, magnesium chlorid, or ammonium chlorid.

In this manner, the cellulose acetates in the. form of bands or of threads may be dyed at temperatures up to boiling temperature without depreciation of luster and without the usual losses, woolly effects, tendering and the like, due, for instance, to saponification.

For example, the acid dye solutions containing one or more dyes may contain chlorid of zinc, of potassium, of sodium, of magnesium, or of barium, or a mixture of them, in presence of one or more protective colloids such as gelatin,v albumen, boiled-off liquors, a tannate, or saponified or'sulfonated fatty acids. The dyestuffs which may be used are any basic, acid or direct dyeing dyestuffs. The dyeing is performed in a liquid bathhpreferably in foam, as described in the spec cation of U. S, Letters Patent Specification of Letters Patent.

Application filed January 5, 1921.

Patented May 17, 1921.

Serial No. 435,225.

No. 123 1732 dated July 31, 1917, in which case the protective colloids together with the salt solution serve at the same time as emulsifiers and foam producers and by their surface activity in common with the color-colloids considerably increase the sorption of the cellulose acetate.

Example.

power of ab-' the bath is heated to boiling and the goods 1 are left in position for another 'quarterof an hour. The dyeing is continued until up to the sample, if necessary with a further addition of dyestufi', and the goods are Washed for a short time in a bath-of soft.

Water containing an oil emulsion.

-What I cla1m 1s:

'1. The herein described process fordye ing cellulose acetates, consisting in carrying out the dyeing operation'with a dyestuifsolution, which contains a weak acid and at least one soluble chlorid.

2.' The herein described process ing cellulose acetates, consisting in carrym out the dyeing operation with a dyestuif solution which contains a weak acid, at least for dyeone soluble chlorid and at least one'protec- I tive colloid. 1

3 The herein described process for dyeing cellulose acetates, consistin in carrying out the dyeing operation wit a dyestuif solution, which contains an organic acid and at least one soluble chlorid.

4. The herein described'process for dyeing cellulose acetates, consisting in carryiriiig out the dyeing operation with a dyestu solution which contains an organic acid, at least one soluble chlorid and at least one protective colloid.

In witness whereof I have hereunto signed my name this eleventh day of December,

1920, in the presence of two subscribing witnesses.

RENE GLAVEL. 

